Quiz on Enzymes

1. How do enzymes speed up a reaction?

• A. by altering the net changes in free energy of the reaction

• B. by providing additional energy to the system

• C. by increasing the substrate concentration

• D. by lowering the activation energy required to begin the reaction

2. An inhibitor is added to an enyme solution and a decrease in enzyme activity was observed. Increasing the substrate concentration does not lead to any observable increase in enzyme activity. Whar can be concluded about the inhibator?

• A. it is a competitive inhibator

• B. it binds to the active site

• C. it is an organic inhibator

• D. it is a non-competitive inhibator

3. Based on the graph below, what is the most likely result of mixing both enzymes with their substrate in a single tube?

• A. only gastric protease would be active if the pH of the mixture was basic

• B. intestinal protease would be more active than gastric protease at pH 4

• C. both enzymes would exhibit the same activity at pH 5

• D. gastric protease would be more active than intestinal protease at pH 6

4. Based on the graph #3, what is a true statement about the relationship between pH and enzyme action?

• A. all enzymes work best at a neutral pH

• B. enzymes function only in 4.0-5.5 pH range

• C. adding more acid does not affect enzymatic activity

• D. the activity of an enzyme is affected by pH

5. Which of the following is associated with noncompetitive inhibitation?

• A. racemization

• B. allotropism

• C. allosterism

• D. Isomerization

6. An enzyme that hydrolyze protein will not act upom starch. This fact is an indication that enzymes are ____.

• A. hydrolytic

• B. synthetic

• C. specific

• D. catalytic

7. Which of the following will cause the rate of enzyme activity to increase linearly?

• A. increasing the enzyme concentration

• B. increasing the substrate concentration

• C. increasing temperature

• D. increasing the pH

8. Proteases, such as trypsin, chymotrypsin, and elastase, selectively hydrolyze peptide bonds. These enzymes exhibit ___ specificity.

• A. linkage

• B. group

• C. stereochemical

• D. absolute

(For questions 9-11, consider the following diagram)

9. Which enzyme shows the greatest change in its reaction rate with the least change in pH?

• A. A

• B. B

• C. C

• D. D

(For questions, 9-11, consider the following diagram)

10. A solution with a pH of 6 contains enzyme C and its substrate. If a base is gradually added to this solution, the enzymatic activity would most likely ___.

• A. remain constant

• B. increase, then decrease

• C. decrease, then increase

• D. decrease constantly